When comparing two things, you often want to state exactly by how much they differ. In Russian, we use the preposition на followed by the accusative case, plus a comparative adjective.
Comparing Prices
To say something is "ten rubles cheaper," use на, the amount in the accusative case, and the comparative adjective дешевле (cheaper) or дороже (more expensive).
For most numbers like десять (ten) and сто (a hundred), the accusative case looks exactly like the nominative. For тысяча (a thousand), the accusative changes to тысячу.
Comparing Age
The exact same structure applies when comparing ages using старше (older). Just as with prices, state the exact amount of time in the accusative case. For example, "by two years" is на два года, and "by five years" is на пять лет.
Significant Differences
If you don't have an exact number, you can use adverbs like значительно (significantly) to describe the difference. Because it is an adverb and not a specific quantity, you do not use на with значительно.
As you discuss income and expenses, you will often mix exact numerical differences and unspecified significant differences in the same context: